[SPARK-40800][SQL][FOLLOW-UP] Add a config to control whether to always inline one-row relation subquery

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/subquery.scala

@@ -746,7 +746,8 @@ object OptimizeOneRowRelationSubquery extends Rule[LogicalPlan] {
     def unapply(plan: LogicalPlan): Option[Seq[NamedExpression]] = {
       // SPARK-40800: always inline expressions to support a broader range of correlated
       // subqueries and avoid expensive domain joins.
-      CollapseProject(EliminateSubqueryAliases(plan), alwaysInline = true) match {
+      val alwaysInline = conf.getConf(SQLConf.ALWAYS_INLINE_ONE_ROW_RELATION_SUBQUERY)
+      CollapseProject(EliminateSubqueryAliases(plan), alwaysInline = alwaysInline) match {
         case Project(projectList, _: OneRowRelation) => Some(stripOuterReferences(projectList))
         case _ => None
       }

sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala

@@ -3097,6 +3097,16 @@ object SQLConf {
       .booleanConf
       .createWithDefault(true)
 
+  val ALWAYS_INLINE_ONE_ROW_RELATION_SUBQUERY =
+    buildConf("spark.sql.optimizer.optimizeOneRowRelationSubquery.alwaysInline")
+      .internal()
+      .doc(s"When true, the optimizer will always inline single row subqueries even if it " +
+        "causes extra duplication. It only takes effect when " +
+        s"${OPTIMIZE_ONE_ROW_RELATION_SUBQUERY.key} is set to true.")
+      .version("3.4.0")
+      .booleanConf
+      .createWithDefault(true)
+
   val TOP_K_SORT_FALLBACK_THRESHOLD =
     buildConf("spark.sql.execution.topKSortFallbackThreshold")
       .doc("In SQL queries with a SORT followed by a LIMIT like " +

sql/core/src/test/scala/org/apache/spark/sql/SubquerySuite.scala

@@ -2470,25 +2470,29 @@ class SubquerySuite extends QueryTest
   test("SPARK-40800: always inline expressions in OptimizeOneRowRelationSubquery") {
     withTempView("t1") {
       sql("CREATE TEMP VIEW t1 AS SELECT ARRAY('a', 'b') a")
-      // Scalar subquery.
-      checkAnswer(sql(
-        """
-          |SELECT (
-          |  SELECT array_sort(a, (i, j) -> rank[i] - rank[j])[0] AS sorted
-          |  FROM (SELECT MAP('a', 1, 'b', 2) rank)
-          |) FROM t1
-          |""".stripMargin),
-        Row("a"))
-      // Lateral subquery.
-      checkAnswer(
-        sql("""
-          |SELECT sorted[0] FROM t1
-          |JOIN LATERAL (
-          |  SELECT array_sort(a, (i, j) -> rank[i] - rank[j]) AS sorted
-          |  FROM (SELECT MAP('a', 1, 'b', 2) rank)
-          |)
-          |""".stripMargin),
-        Row("a"))
+      Seq(true, false).foreach { enabled =>
+        withSQLConf(SQLConf.ALWAYS_INLINE_ONE_ROW_RELATION_SUBQUERY.key -> enabled.toString) {
+          // Scalar subquery.
+          checkAnswer(sql(
+            """
+              |SELECT (
+              |  SELECT array_sort(a, (i, j) -> rank[i] - rank[j])[0] AS sorted
+              |  FROM (SELECT MAP('a', 1, 'b', 2) rank)
+              |) FROM t1
+              |""".stripMargin),
+            Row("a"))
+          // Lateral subquery.
+          checkAnswer(
+            sql("""
+                  |SELECT sorted[0] FROM t1
+                  |JOIN LATERAL (
+                  |  SELECT array_sort(a, (i, j) -> rank[i] - rank[j]) AS sorted
+                  |  FROM (SELECT MAP('a', 1, 'b', 2) rank)
+                  |)
+                  |""".stripMargin),
+            Row("a"))
+        }
+      }
     }
   }